SSS11.1

Development of New Technologies in Soil Conservation and Eco Sustainability

Soil conservation is a necessary action to achieve a sustainable world because of the crucial role that soils play in the earth system. Reproducible and precise methods are vital to obtain credible data in the soil studies. This session will provide the premier forum for the presentation of new advances in the fields of experimental, theoretical, and applied soil conservation and eco sustainability. The topics of interest for submission may focus on the new technologies regarding soil conservation and eco sustainability together with the important results related to the novel approaches. In details, we seek abstracts on the following topics: erosional and depositional processes, watershed management, soil evolution and weathering, soils and surface processes, land degradation and restoration, environmental sustainability, resource management, sustainable cities, hazardous substances and detection techniques. The promoted methodologies include remote sensing, lab experiments, field experiments, environmental regulation and monitoring, economic technology and instruments, and modeling and decision support tools.

Co-organized by GI6
Convener: Xiangzhou Xu | Co-conveners: Paolo Tarolli, Tingwu Lei, Peiqing Xiao
vPICO presentations
| Fri, 30 Apr, 09:00–12:30 (CEST)

Session assets

Session materials Session summary

vPICO presentations: Fri, 30 Apr

Chairpersons: Tingwu Lei, Peiqing Xiao, Xiangzhou Xu
09:00–09:05
SLOT I: New technologies in soil and water conservation. Friday, 30 Apr, 09:00–10:30 CET; 15:00–16:30 Beijing
09:05–09:15
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EGU21-14858
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ECS
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solicited
Margot Peluchon, Didier Michot, Blandine Lemercier, Sylvain Busnot, Thierry Morvan, Mario Fajardo, Sebastien Salvador-Blanes, Marine Lacoste, Frédéric Darboux, and Nicolas Saby

The measurement of aggregate stability is an important indicator of soil quality and is widely used for monitoring soil condition. The SLAKES mobile app is an alternative tool to laboratory-based methods to measure soil aggregate stability. It provides aggregate stability measurements through Slaking Index (SI) with SI close to 0 suggesting high stability and values above 7 suggesting minimum stability. As the duration of this low-cost experiment is only 10 minutes, SLAKES is very attractive for scientists and no-scientists. SLAKES was implemented in Australia and has proven its efficiency in several studies.

This study was conducted to determine whether the SLAKES mobile app could be adapted to French soils and then could be an alternative to the Mean Weight Diameter (MWD) method, normalized in France (ISO 10390). More specifically, the three main objectives were: (i) determining whether the aggregate stability measurements depend on the phones used for the experiment, (ii) estimating the number of measurements necessary to get reliable results, (iii) determining whether the app has the ability to detect the effect of contrasting soil managements previously shown using the MWD method.

The study was performed on silty loam soils from EFELE (Effluents d’Elevage et Environnement) experimental site at le Rheu (Brittany, France) which is part of the French “Organic Residues” research observatory (SOERE PRO). The experimental design combines two different tillage practices (conventional tillage and shallow tillage) with two fertilizer treatments (mineral and organic (cattle manure)) randomly replicated three times. Soil samples were collected in March 2017 at both 0-15 cm and 15-25 cm depth from the 12 plots. 

The SI was measured on three aggregates simultaneously and this measurement was repeated 15 times for each sample which provided 45 SI per sample. Outliers above SI=11 were removed before statistical treatments. Four different phones of the same brand and generation were used to measure SI.

An analysis of variance showed that the effect of the smartphone on SI measurements was not significant (p-value = 0.73, 0.88, 0.067 for 3 different samples). The SLAKES results showed comparable significant separation of means (p < 0.0001) between each soil management than the MWD method. According to the results of an analysis of variance, SI was significantly lower in reduced tillage than in conventional tillage condition (p-value = 2.10-16). These results indicate a higher soil stability in reduced tillage. Yet, the analysis of variance did not underline any effect of fertilization on the SI (p-value = 0.28), as previously found with the MWD method.

This study proved that a relatively simple mobile app can detect the effect of soil management practices on aggregate stability with a similar performance than the MWD method. This conclusion was reinforced by the existing correlation between the SI and the MWD index (p-value = 0.00059, R2 = 0.39). We recommend to perform similar experiments on other sampling campaigns or in other pedological and soil management contexts taking at least 15 measures per sample.

How to cite: Peluchon, M., Michot, D., Lemercier, B., Busnot, S., Morvan, T., Fajardo, M., Salvador-Blanes, S., Lacoste, M., Darboux, F., and Saby, N.: Evaluation of SLAKES, a smartphone application for quantifying aggregate stability, in soils with contrasting managements, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14858, https://doi.org/10.5194/egusphere-egu21-14858, 2021.

09:15–09:20
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EGU21-16324
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solicited
Sudabeh Gharemahmudli, Seyed Hamidreza Sadeghi, and Ali Najafinejad

Abstract: Soil erosion is a major concern worldwide and serious eco-environmental problem and an important driver of soil loss and water sources. Hence, it is necessary to provide appropriate biological solutions and implement proper measures aimed at controlling soil erosion and runoff generation. Application of soil amendments and additives is one of the technical-managerial approaches considered to enhance soil stability against degradation agents. One of the new and biological technique in the conservation and management of soil and water resources is the use of native soil microorganisms extracted from the same area. Soil microorganisms are resistant to various environmental stresses such as high temperature, drought, UV, freezing and other stresses. In response to extreme and variable conditions, consortia of several species can develop firm layered structures, microbial mats, or biofilms. The inoculated soil microorganisms, especially bacteria and cyanobacteria through their polysaccharide and exopolysaccharide secretions, cellular elasticity, connecting to soil fine particles via cell adhesiveness. They also stay in the space between proliferation and developing filament networks and binding to aggregates. Besides water abstraction of rainfall and the creation of surface soil microchannels, they increase soil permeability and resistance stress which can tackle the effects of raindrop splash through water absorption and creation a protective layer around soil particles. It ultimately reduces runoff yield and soil loss. Soil microorganisms also can contribute considerably to soil organic matter and exert critical control over soil organic carbon stabilization in the global carbon cycle, soil recovery and stability as well as increase nutrient accumulation and soil fertility. According to the study conducted by the authors, by extraction and proliferation of soil microorganisms from an area under freezing-thawing conditions, their performance was evaluated in laboratory conditions. The results of their research showed that the direct inoculation of soil microorganisms into the soil decreased mean runoff volume by 73% and increased time to peak by 56%. Further, a decrease of some 78% in mean sediment concentration and a decrease of 89% in total soil loss were ascertained. Hence, creating artificial biological soil crusts by native soil microorganism inoculation is novel step in achieving biological tools to increase soil stability against soil erosion. The direct inoculation of soil microorganisms therefore could be supposed as a rapid, persistent, environmentally sound, economically efficient, and technically appropriate biological tool for conserving soil and water resources.

How to cite: Gharemahmudli, S., Sadeghi, S. H., and Najafinejad, A.: Functionality of Soil Microorganisms in Bio-conservation of Water and Soil, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16324, https://doi.org/10.5194/egusphere-egu21-16324, 2021.

09:20–09:22
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EGU21-4061
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solicited
Youcai Kang, Jianen Gao, Hui Shao, and Yuanyuan Zhang

Abstract: Climate and land-use change are the two main driving forces that affect watershed hydrological processes. Separately assessing the impacts of climate and land use change on hydrology is important for water resource management. In this research, the SWAT (Soil and Water Assessment Tool) and statistical methods were employed to evaluate the effects of climate and land-use change on surface hydrology in the hilly-gully region of the Loess Plateau. The results showed that both the temperature and potential evapotranspiration (PET) had significant upward trends (p < 0.05), while the precipitation presented a slightly downward trend in the Yanhe watershed during 1982-2012. The contribution of precipitation to streamflow is concentrated in the flooding periods (from July to September), the average contribution rate of surface runoff on stream flow accounted for 55%, of which the flooding period accounted for 40%. With the 2.17% of slope farmland transformed to the forest and grassland, the average runoff coefficient decreased from 0.36 to 0.15 during 1982-2012. The impact of land use change on soil water content is mainly happened in the upstream stream, while the dominated factor converted to climate from northwest to southeast in the Yanhe watershed. The Evapotranspiration was more sensitive to land-use change than climate variability in all sub-basins, and increased by 209% with vegetation restoration in the Yanhe watershed. Therefore, the impacts of climate variation and land use change on surface hydrological processes were heterogeneity in different geographical regions, climate is the main factor to influence the runoff, while the land use is the dominated factor to evapotranspiration. The quantitative assessment the influence of climate variability and land-use change on hydrology can provide insight into the extent of land use/cover change on regional water balance, and develop appropriate watershed management strategies on the Loess Plateau.

Keywords: climate shift, human activities, hydrological processes, SWAT, the Loess Plateau

Funding: This study was funded by the National Natural Science Foundation of China (No. 41877078, 41371276), Key research and development project of Shaanxi Province (2020ZDLSF06-03-01), National Key Research and Development Program of China (No. 2017YFC0504703) and Knowledge Innovation Program of the Chinese Academy of Sciences (No. A315021615).

 

How to cite: Kang, Y., Gao, J., Shao, H., and Zhang, Y.: Impact of Climate Variability and Land Use Change on Surface Hydrological Processes in the Hilly-Gully Region of the Loess Plateau, China, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4061, https://doi.org/10.5194/egusphere-egu21-4061, 2021.

09:22–09:24
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EGU21-4955
Luca Mauri, Eugenio Straffelini, and Paolo Tarolli

Land degradation represents one the main issue affecting agricultural systems, especially in those areas that are characterized by agricultural practices on steep hillslopes. The occurrence of erosion processes and landslides is closely linked with the presence of road networks. Factors like inefficient of absent drainage systems, wasteful road management and not optimal planning, as well as specific geomorphological and hydrological elements directly encourage landslides activation. In this connection, the combined use of Remotely Piloted Aircraft Systems (RPAS) and photogrammetric techniques (e.g. Structure from Motion; SfM) allowed to elaborate multi-temporal (therefore 4D) high-resolution Digital Elevation Models (DEMs), so as to detect geomorphological changes affecting earth surface at specific spatial and temporal scale. At the same time, the adoption of several models allows to compute specific hydrological analysis, for instance investigating the alteration of surface water flow dynamics due to the presence of specific features like roads. In this context, this research aims to propose a multi-temporal analysis of the road-induced water flow alterations in a shallow landslide-prone agricultural system. SIMWE model (Mitasova et al., 2013) was applied focusing on different geomorphic and rainfall scenarios, looking at the presence of the road network within the study area and assuming its absence through specific DEM post-processing procedures. In this connection, the possibility to perform multi-temporal hydrological simulations at the hillslope scale, to analyse the role played by the road in landslides activation is still a challenge to be investigated. In this article, we considered a case study placed in northern Italy, where two shallow landslides were observed below a rural road located within a terraced vineyard. Multi-temporal hydrological simulations were conducted to further analyse the evolution of road induced water flows deviations, thus stimulating landslides occurrence on the detected hillslopes. Maximum water depths equal to 0.60 m and 0.46 m were noticed close to specific zones of the road sections located above the first and the second landslide respectively. The simulations computed assuming the absence of the road revealed the lack of water flows deviations involving the landslide zones, underlining the fact that the road absence would avoid significant changes in water flow paths toward the collapsed zones. The key role played by the road in water flows deviation and in the evolution of the observed land degradation dynamics was attested through the comparison of the thematic maps resulted from each simulation. This work could be a solid starting point for further analyse the roads impact on runoff dynamics at a wider scale, aiming to plan and propose mitigation interventions so as to reduce the occurrence of future risk scenarios. At the same time, efficient design of drainage systems along the roadway could be conducted starting from the outcomes presented in our research, so as to prevent the activation of similar land degradation processes.


Reference
Mitasova H., Barton C.M., Ullah I., Hofierka J., Harmon R.S. 2013. GIS-Based Soil Erosion Modeling. Treatise on Geomorphology (3), 228-258.

How to cite: Mauri, L., Straffelini, E., and Tarolli, P.: Modelling of overland flows in a terraced vineyard affected by road-induced shallow landslides , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4955, https://doi.org/10.5194/egusphere-egu21-4955, 2021.

09:24–09:26
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EGU21-1949
Pan Zhang and pingqing Xiao

Coarse sediment of the Yellow River in the complex erosion area of the Pisha sandstone region of the Ordos Plateau is deposited on the downstream riverbed, posing a threat to the flood control safety of the river. The study of sediment particles in this erosion process can deepen the understanding of the erosion process, provide a theoretical basis for the establishment of an erosion prediction model, reveal the internal law of composite erosion, and guide the planning and design of soil and water conservation and the allocation of soil and water conservation measures. In this study, complex erosion indoor tests were carried out through the artificial rainfall-wind-freezing-thawing cycle solid model. The enrichment rate (ER), fractal dimension, and median diameter (d50) of soil particles were used to quantify the size distribution characteristics of sediment particles under different erosion dynamics. The coarse sediment was first transported in the process of soil erosion because of the special texture and terrain characteristics of Pisha sandstone soil. Moreover, the degree of heterogeneity of sediment under complex erosion was larger than that under water erosion. The effect of wind could aggravate the instability of the erosion dynamic system. Under the combined action of freezing-thawing, wind, and water, the particle size composition changed greatly, and the erosion energy was extremely unstable. The effect of complex erosion created conditions for the coarse sediment transportation. Under the freezing-thawing-wind-water combined action, the particle size of eroded sediment was the coarsest, and that of water erosion was the smallest. We concluded that the reason why the Pisha sandstone area has become the core area of the concentrated source of coarse sediment in the Yellow River is related not only to the special nature of the Pisha sandstone soil itself but also to the effect of complex erosion.

How to cite: Zhang, P. and Xiao, P.: Particle-size distribution of transported sediment in the Pisha sandstone slope under the influence of complex erosion, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1949, https://doi.org/10.5194/egusphere-egu21-1949, 2021.

09:26–09:28
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EGU21-14196
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ECS
Gayatri Singh

The present study is to quantify the spatial-temporal pattern of the Land Use/ Land Cover Change (LULCC) during a decade (i.e., 2010 to 2020) in the Dehradun city which is situated in the foothills of the Himalaya, using Landsat data. The study helps in identifying the major bio-physical factors governing LULCC through modern geospatial techniques. Change detection shows that the study area experienced an increase in its urban area from 2010 to 2020 and a comparatively decrease in cropland and forest area. This was due to an increase in its urban population, rapid increase in industrialization and tourism during the same period. The change detection analysis further shows that 2010-2020, associated with change in croplands, change in built-up, forest lands, change in water-bodies, water levels, and rainfall. With comparison of above results and collected socio-economic data in this region, the impact of changing land use & bio-physical/ economic factors on agricultural profitability were analyzed. The result of this study could thus lead to a detailed and lucid spatiotemporal assessment of the major bio-physical factors. It is expected that the study will help in facilitating better policy making and infrastructure development for industries and urbanization.

How to cite: Singh, G.: A study of decadal Land use-land cover change in Dehradun city., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14196, https://doi.org/10.5194/egusphere-egu21-14196, 2021.

09:28–09:30
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EGU21-7841
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ECS
Yueqiang Shen, Tonglu Li, Dongyang Li, and Tingkai Nian

Erosion effect plays a significant role in the run-out process of a rapid loess landslide. This effect is manifested in bed entrainment and frontal plowing on terraced material during movement, leading to the volume amplification. Therefore, an improved two-layer model is proposed to describe the frontal plowing and bed entrainment in this paper. In addition, the bed entrainment rate is further calculated by introducing the bed entrainment physical model. The sliding mass and plowed material are assumed to be immiscible in this model, and the mechanical behaviour between the materials is simulated by considering the interaction force between the two layers. Furthermore, the governing equations are deduced from the mass and momentum conservation. It is then applied to analyze a typical rapid loess landslide, Dongfeng landslide. The results indicate that the bed entrainment and frontal plowing have a significant impact on the mobility of the landslide, which is mainly shown in the following two aspects: 1) the bed entrainment effect significantly increases the speed and volume of the landslide; 2) The frontal plowing effect will impede the motion of the frontal sliding mass, and there is a clear separation between the sliding mass and the plowed material, which is more consistent with the field observations. The improved two-layer model proposed in this paper can provide more reliable assessment to describe the rapid loess landslides with erosion.

How to cite: Shen, Y., Li, T., Li, D., and Nian, T.: Erosion effect in the movement process of rapid loess landslide using an improved two-layer model, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7841, https://doi.org/10.5194/egusphere-egu21-7841, 2021.

09:30–09:32
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EGU21-1209
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ECS
Liu Wenxiang, Yu Hanqing, and Lu Yang

A large number of radionuclides, produced by nuclear accidents or nuclear waste, may cause radioactive contamination in the agricultural and aquatic ecosystems. Under these circumstances, it is necessary to optimize the remediation of agricultural areas polluted by radionuclides using innovative monitoring and prediction techniques. To mitigate radioactive contamination in farmland soil and effectively protect groundwater, some measures should be taken against on field investigation, laboratory experiment and model prediction. In this study, the HYDRUS-1D model was used to simulate the vertical migration of 137Cs and 60Co in farmland soil in northern China calibrating by the soil lysimeter experiment, and the scenario simulations of 137Cs and 60Co migration were conducted under different radioactive levels. Results showed that the order of sensitivity in saturated water content (θs), residual water content(θr), saturated hydraulic conductivity(Ks) and distribution coefficient (Kd) applied in HYDRUS 1D model was Kd > θs > θr >Ks. The simulated concentrations ​​of 137Cs and 60Co in Brown soil and Aeolian sandy soil on day 175 and 355 were significantly positively correlated with the measured values​​ (r>0.90, p<0.01). The verification results showed that the predictive values on the 577th day were also significant positive correlated with the measured values ​​(r>0.90, p<0.01). The RMSE, CRM and NRMSE calculating by simulated and measured values ​​of 137Cs and 60Co in soil were very small, indicating that HYDRUS 1D can be used to simulate the migration of radionuclides in farmland soil. Scenarios simulation results revealed that radionuclides were concentrated in the surface layer within 5 cm, but the migration depth has exceed 10 cm soil depth, and even reaches up to 23.5 cm depth at high concentration level. The surface soil should be cleaned timely to protect groundwater with high level from radioactive contamination and further study should be done about horizontal transport and numerical simulation.

How to cite: Wenxiang, L., Hanqing, Y., and Yang, L.: Risk evaluation of radionuclides contamination on soil and groundwater under different scenarios simulating by HYDRUS-1D, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1209, https://doi.org/10.5194/egusphere-egu21-1209, 2021.

09:32–09:34
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EGU21-9443
Kabral Mogos Asghede and Dawit Berhane Hagos

Abstract: Presently the water-supply problem in the Asmara area has reached to a critical level. Using a GIS-based method this study identifies the spatial variability of the groundwater quality in the Asmara Area which could be an alternative source. The results show that, the Total Dissolved Solids (TDS), Total Hardness (TH), Chloride (Cl-), Nitrates (NO3-), Calcium (Ca), Magnesium (Mg), Sulphate (SO4) and pH are 791.71, 569.12, 124.41, 64.46, 155.60, 46.64, 159.26 and 7.72 mg/L, respectively. Moreover, the zone map of the developed groundwater quality shows that the potable water without treatment covers about 35%, and the potable water in the absence of better alternate sources covers about 58% of the total area. The remaining, 7.04% of the total, falls under non-potable groundwater quality. The verification of the spatialanalysis demonstrates that the framework is the first one in Eritrea and could be used as a potential prediction for the assessment of the spatial groundwater quality in the countries with further verification results. Hence, the delineation of groundwater quality zones and establishment of a GIS-based database will easily help the decision makersto monitor and plan the utilization of the groundwater resources in the study area.

Keywords: Groundwater quality; physicochemical parameters; GIS spatial analysis; framework

How to cite: Asghede, K. M. and Hagos, D. B.: A GIS-based assessment of spatial groundwater quality for drinking purposes in Asmara City, Eritrea, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9443, https://doi.org/10.5194/egusphere-egu21-9443, 2021.

09:34–09:36
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EGU21-3963
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ECS
Taicong Liu, Li Rong, Xingwu Duan, and Zhe Chen

Abstract: Land use is one of the most important forms in agricultural production. Non-appropriate land use can cause deterioration of physical, chemical and biological properties of soil, thus affecting sustainable agriculture. Earlier reports showed that land use drastically altered microbial community composition. However, the mechanism of land use on microbial communities is still not fully understood. In the present study, we focus on the dry hot valley, characterized by high temperature and low humility, to test whether soil properties from four primary land uses including the land conversion from farmland (SLC), sugarcane land (SL), maize land with conventional tillage (CT) and bare land (BL) have different influences on soil microbial communities. The results showed that land uses altered bacterial and fungal community composition. In SL and BL, we found the respective absence of a kind of fungi at phylum the level. The abundances of several bacterial phyla in SL such as Gemmatimonadets and Acidobacteria associated with promoting mineralization were higher than that in other land uses. RDA indicated that bacterial communities were influenced by soil total nitrogen, total organic carbon and available potassium contents, and fungal communities were dominated by available potassium contents. SEM (structural equation model) showed that land use has direct and indirect effects on bacterial composition, while only indirect effects on fungal by land use. Land use indirectly affected bacterial composition through effects on soil moisture, clay and available potassium contents, whereas through effects on clay and available potassium for fungal composition. Land use exhibited greater impacts on bacterial composition than fungal composition, implying bacteria was more sensitive to land use changes compared to fungi in the dry-hot valley. Considering the low level of total potassium in soil under SL and CT, elevated potassium fertilizer would be a beneficial pathway to improve soil microbial composition and soil nutrients in the dry hot valley.

Key word: Land use, Soil microbial community, Dry-hot valley, Soil properties, Structural equation model.

How to cite: Liu, T., Rong, L., Duan, X., and Chen, Z.: Land use types influence soil microbial community through effects on soil properties in the dry-hot valley region in southwestern China, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3963, https://doi.org/10.5194/egusphere-egu21-3963, 2021.

09:36–09:38
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EGU21-7695
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ECS
Yongsheng Cui, Chengzhong Pan, Geng Zhang, Zhanwei Sun, and Fuxing Wang

      Litter accumulates yearly since vegetations were widely planted for reforestation, and it plays an important role in hydrologic cycling. There is little information on the effects of litter on re-allocation of rainfall processes. Eight runoff plots were established in the Pinus tabulaeformis stand with four litter (needle-leaf) masses (0, 0.6, 1.2, 1.8 kg/m2), and the surface runoff (R), evaporation (E), infiltration and soil moisture dynamics were measured throughout the mainly rainy season from August 4 to September 28 in the Loess Plateau. The results showed that, soil evaporation mainly occurred in daytime for bare soil, and decreased with increasing litter masses, and litter cover is prone to hinder the heat and water exchange between soil and atmosphere, especially for the soil layer 0~5 cm. Litter cover greatly decreased surface runoff, and it may hinder infiltration at the beginning of rainy season, but increasing soil water storage (SWS) with deeper infiltration depth for the long run, especially for the litter masses 1.2 and 1.8 kg/m2. With the litter covered, the ratio of R to precipitation (P) was less than 10%, no matter it was heavy rain or light rain. However, the proportion of R was amplified when the rainfall was intense for the bare soil. And the ratio of E to P was always below 10% for all treatments, except for light rainfall. With the increased litter masses, the proportion of R and E all decreased, and the SWS/P has well nonlinear positive relationship with litter masses, and it was proved that more than a half of rainfall was stored even for bare soil. This study may helpful to better understanding the effects of litter on hydrological response, and promotes practical measurements to the management of precipitation in a forest stand view.

How to cite: Cui, Y., Pan, C., Zhang, G., Sun, Z., and Wang, F.: Effects of litter cover on partitioning of natural rainfall for plantation Pinus tabulaeformis forest in the Loess Plateau of China, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7695, https://doi.org/10.5194/egusphere-egu21-7695, 2021.

09:38–09:40
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EGU21-4363
Qiufen Zhang, Xizhi Lv, Rongxin Chen, Yongxin Ni, and Li Ma

The slope runoff caused by rainstorm is the main cause of serious soil and water loss in the loess hilly area, the grassland vegetation has a good inhibitory effect on the slope runoff, it is of great significance to reveal the role of grassland vegetation in the process of runoff generation and control mechanism for controlling soil erosion in this area. In this study, typical grassland slopes in hilly and gully regions of the loess plateau were taken as research objects. Through artificial rainfall in the field, the response rules of slope rainfall-runoff process to different grass coverage were explored. The results show that: (1) The time for the slope flow to stabilize is prolonged with the increase of vegetation coverage, and shortened with the increase of rainfall intensity; (2) At 60 mm·h −1 rainfall intensity, the threshold of grassland vegetation coverage is 75.38%; at 90 mm·h −1 rainfall intensity, the threshold of grassland vegetation coverage is 90.54%; at 120 mm·h −1 rainfall intensity, the impact of grassland vegetation coverage on runoff is not significant; (3) the Reynolds number and Froude number of slope flow are 40.07‒695.22 and 0.33‒1.56 respectively, the drag coefficient is 1.42‒43.53. Under conditions of heavy rainfall, the ability of grassland to regulate slope runoff is limited. If only turf protection is considered, about 90% of grassland coverage can effectively cope with soil erosion caused by climatic conditions in loess hilly and gully regions. Therefore, in loess hilly areas where heavy rains frequently occur, grassland's protective effect on soil erosion is obviously insufficient, and investment in vegetation measures for trees and shrubs should be strengthened.

How to cite: Zhang, Q., Lv, X., Chen, R., Ni, Y., and Ma, L.: Regulation and Critical Threshold of Grass Cover on Slope Runoff in LoessHilly Gully Region under Artificial, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4363, https://doi.org/10.5194/egusphere-egu21-4363, 2021.

09:40–09:42
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EGU21-4131
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ECS
Xizhi Lv, Shaopeng Li, Yongxin Ni, Qiufen Zhang, and Li Ma

In the past 60 years, climate changes and underlying surface of the watershed have affected the structure and characteristics of water resources to a different degree It is of great significance to investigate main drivers of streamflow change for development, utilization and planning management of water resources in river basins. In this study, the Huangshui Basin, a typical tributary of the upper Yellow River, is used as the research area. Based on the Budyko hypothesis, streamflow and meteorological data from 1958-2017 are used to quantitatively assess the relative contributions of changes in climate and watershed characteristic to streamflow change in research area. The results show that: the streamflow of Huangshui Basin shows an insignificant decreasing trend; the sensitivity coefficients of streamflow to precipitation, potential evapotranspiration and watershed characteristic parameter are 0.5502, -0.1055, and 183.2007, respectively. That is, an increase in precipitation by 1 unit will induce an increase of 0.5502 units in streamflow, and an increase in potential evapotranspiration by 1 unit will induce a decrease of 0.1055 units in streamflow, and an increase in the watershed characteristic parameter by 1 unit will induce a decrease of 183.2007 units in streamflow. Compared with the reference period (1958-1993), the streamflow decreased by 20.48mm (13.59%) during the change period (1994-2017), which can be attribution to watershed characteristic changes (accounting for 73.64%) and climate change (accounting for 24.48%). Watershed characteristic changes exert a dominant influence upon the reduction of streamflow in the Huangshui Basin.

How to cite: Lv, X., Li, S., Ni, Y., Zhang, Q., and Ma, L.: Quantitative estimation on contribution of climate changes and watershed characteristic changes to decreasing streamflow in the Huangshui Basin, China, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4131, https://doi.org/10.5194/egusphere-egu21-4131, 2021.

09:42–09:44
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EGU21-1540
Cuiting Dai, Yiwen Zhou, Zhaoxia Li, Tianwei Wang, and Jun Deng

Macropores have been widely recognized as preferential pathways for the rapid movement of water into soils. The objectives of this study were to characterize soil macropore structures using X-ray computed tomography (CT) and to explore the relationships between macropore characteristics and hydraulic properties of stony soils. To achieve these, a total of 18 soil columns were sampled from six sites (three sites covered with grass and three sites with forest) with stony soils located in a mountain watershed in the Three Gorges Reservoir Area of Central China. Field infiltration experiments were carried out at the sampling sites under near-saturated conditions using a tension disc infiltrometer. The three-dimensional macropore structures were visualized from X-ray CT images, and total macroporosity, connected macroporosity, macropore density, specific surface area, degree of anisotropy, fractal dimension, and hydraulic radius were characterized. The results showed that the largest total macroporosity and connected macroporosity were observed at forest sites. The macropore structure with high connectivity could facilitate greater water infiltration into the soils. The near-saturated hydraulic conductivity Kh was significantly higher at the forest sites than at the grassland sites at four water pressure heads. The stony soils studied had heterogenous macropore systems with large and well-connected macropores. The macroporosity of macropores with equivalent diameters between 0.5 and 2 mm was found best to predict the near-saturated hydraulic conductivity. Our study provides a helpful technique for a better understanding of stony soil macropores and hydraulic properties by a combination of 3D visualization methods and traditional hydraulic analysis.

How to cite: Dai, C., Zhou, Y., Li, Z., Wang, T., and Deng, J.: Characterizing and linking macropore structure characteristics to water infiltration in stony soils, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1540, https://doi.org/10.5194/egusphere-egu21-1540, 2021.

09:44–09:46
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EGU21-16497
Hongliang Tang

Abstract: As a huge metropolis, the highly intensive development and utilization of underground space in Shanghai has become the distinct trend of urban construction. Combined research among more than 100 industrial and civil construction projects in the city finds that soil erosion during the construction of underground works accounts for a significant proportion (50%~60%) of the totality of soil erosion or degradation. In order to further promote the precise management and control of water and soil conservation in the procedure of construction engineering projects, this paper analyzes the relationship between foundation pit supporting measures and water and soil conservation results in typical underground engineering examples. Through summing up the high frequency risk points of water and soil loss caused by underground engineering of housing construction projects in Shanghai, several positive methods for preventing and controlling water and soil erosion could be contributed correspondingly for the future work, such as pretreatment of the drilling caving of bored piles, and making full use of the soil produced by underground excavation.

Key words: underground engineering; risk analysis; water and soil conservation measures

How to cite: Tang, H.: Soil erosion and its prevention measures during the construction period of underground engineering: a case study in the city Shanghai, China, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16497, https://doi.org/10.5194/egusphere-egu21-16497, 2021.

09:46–10:30
Break
Chairperson: Paolo Tarolli
SLOT II: New technologies in ecological sustainability. Friday, 30 Apr, 11:00–12:30 CET; 17:00–18:30 Beijing
11:00–11:10
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EGU21-13919
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ECS
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solicited
Ke Liang and Binghui He

Severe soil erosion occurs in southwestern China owing to the large expanses of human disturbance and sloping land. This field monitoring study was conducted during the rainy season to record the rainfall events, runoff, sediment yield, nitrogen, and phosphorous loss in 20-, 40-, and 60-m plots under conditions of artificial disturbance or natural restoration on a 15° slope in the purple soil area of southwestern China. The concentrations and loss amounts of total nitrogen (TN), total dissolved nitrogen (TDN), ammonium-nitrogen (NH4-N) and nitrate-nitrogen (NO3-N), total phosphorus (TP), total dissolved phosphorus (TDP) and orthophosphate (PO4-P) were comparatively determined. The highest N concentration was observed in long duration and soft rainfall events across all plots. The highest P concentration in artificial disturbed plots was found in long duration and intensive rainfall events while it was recordeds for measured variables were dominantly recorded under the long duration and lowest soft rainfall events in naturally restored plots intensity., while The the highest loss amounts for N and P in different forms for these variablesalmostmostly appeared under high rainfall intensity. Land disturbances differed orthophosphate PO4-P concentration in 20--m plot and and loss amounts of of measured variables N and P with different forms across in all plots. Plot lengths differed total dissolved phosphorus TDP concentration in natural restored plot and loss amounts of total dissolved nitrogenTDN and orthophosphate PO4-P in artificially disturbed plots. Naturally restoration reduced loss amounts of total nitrogen and total phosphorus by 69.4%62.14-79.05% and 79.28-83.43% TN, 68.8% TDN, 71.2% NH4-N, 74.3% NO3-N, 81.5% TP, 71.9% TDP and 70.0% PO4-P loss amounts comparedrelative to artificial disturbance, respectively. There were significant interrelationships among N and P concentrations in different forms in two land disturbance plots, while nitrate-NO3-nitrogenN concentration hadwas significantly negatively negative correlatedion with rainfall intensity and runoff rate in artificialally disturbanceed plots. Rainfall intensity was logarithmically correlated with TN, NO3-N concentrations in artificially disturbed plots and with NO3-N concentration in naturally restored plots. Runoff rate was logarithmically correlated with TN, TDN and NO3-N concentrations in artificially disturbed plots. Our results highlight the effects of land disturbance and plot length on nutrient losses in sloping land.

How to cite: Liang, K. and He, B.: Naturally rainfall-induced changes in runoff-associated nitrogen and phosphorus losses in purple soil area: roles of land disturbance and plot length, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13919, https://doi.org/10.5194/egusphere-egu21-13919, 2021.

11:10–11:15
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EGU21-1903
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ECS
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solicited
Zhihui Wang and Peiqing Xiao

Conversion of cropland to forest/grassland has become a key ecological restoration measure on the Loess Plateau since 1999. Accurate mapping of the spatio-temporal dynamic information of conversion from cropland into forest/grassland is necessary for studying the effects of vegetation change on hydro-ecological process and soil and water conservation on the Loess Plateau, China. Currently, the accuracy of change detection of farmland and forest/grassland at 30-m scale in this area is seriously affected by insufficient temporal information from observations and irregular fluctuations in vegetation greenness caused by precipitation and human activities. In this study, an innovative method for continuous change detection of cropland and forest/grassland using all available Landsat time-series data. The period with vegetation coverage is firstly identified using normalized difference vegetation index (NDVI) time series. The intra-annual NDVI time series is then developed at a 1-day resolution based on linear interpolation and S-G filtering using all available NDVI data during the period when vegetation types are stable. Vegetation type change is initially detected by comparing the NDVI of intra-annual composites and the newly observed NDVI. Finally, the time of change and classification for vegetation types are determined using decision tree rules developed using a combination of inter-annual and intra-annual NDVI temporal metrics. Validation results showed that the change detection was accurate, with an overall accuracy of 88.9% ± 1.0%, and a kappa coefficient of 0.86, and the time of change was successfully retrieved, with 85.2% of the change pixels attributed to within a 2-year deviation.

How to cite: Wang, Z. and Xiao, P.: Spatio-temporal detection of converting from cropland to forest/grassland on the Loess Plateau using all available Landsat time-series images, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1903, https://doi.org/10.5194/egusphere-egu21-1903, 2021.

11:15–11:17
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EGU21-2556
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ECS
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solicited
Yawen Li, Xingwu Duan, Ya Li, Yuxiang Li, and Lanlan Zhang

Changes in land use can result in soil erosion and the loss of soil organic carbon (SOC). However, the individual contribution of different land use types on SOC variability as well as the combined impacts of land use and soil erosion are still unclear. The aims of the present study were to: (1) evaluate soil erosion and SOC contents under different land use types, (2) identify the influences of soil depth and land use on SOC content, and (3) determine the contribution of land use and soil erosion on SOC variability. We assessed the SOC and total soil nitrogen (TSN) contents under three types of land use in the dry-hot valley in southern China. Caesium-137 (137Cs) and excess lead-210 (210Pbex) contents were also measured to determine soil-erosion rates. Land use was found to significantly affect soil erosion, and erosion rates were higher in orchard land (OL) relative to farmland (FL), which is in contrast with previous study results. SOC and TSN contents varied significantly between the three land use types, with highest values in forest land (FRL) and lowest values in OL. SOC was found to decrease with decreasing soil depth; the highest rate of reduction occurred in the reference site (RS), followed by FRL and FL. The interaction between soil erosion and land use significantly impacted SOC in the soil surface layer (0–12 cm); the direct impact of soil erosion accounted for 1.5% of the SOC variability, and the direct or indirect effects of land use accounted for the remainder of the variability. SOC content in deep soil was mainly affected by factors related to land uses (89.0%). This quantitative study furthers our understanding on the interactive mechanisms of land use and soil erosion on changes in soil organic carbon.

How to cite: Li, Y., Duan, X., Li, Y., Li, Y., and Zhang, L.: Interactive effects of land use and soil erosion on soil organic carbon in the dry-hot valley region of southern China, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2556, https://doi.org/10.5194/egusphere-egu21-2556, 2021.

11:17–11:19
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EGU21-6173
Guoxian Huang, Xinghua Li, Mingdong Sun, and Kun Lei

Dahuofang reservoir (DHFR) is one of the most important drinking water sources in Liaoning province, China. The processes of total phosphorus (TP) concentration, flux and retention rate are very important to the water quality management and drinking water safety for the reservoir. Based on the monitoring data of meteorology, hydrology, water quality and sediment, etc. at the controlled stations of Dahuofang catchment during 1992-2017, The suspended sediment centration(SSC) and TP concentration variation and differences from upper to lower reach of DHFR  during floods in 2010 and 2013 are analyzed and compared respectively. Based  on the  mass balance equation of TP and the related fluxes formula at the different boundaries, the stocking processes in both the overlying water and the active surface sediment layer are solved. The results revealed the TP accumulation variation in the overlying water and the surface sediment layer, together with the controlling mechanism of TP concentration in overlying water under different floods events. Moreover, the results discovered that the combination of flood and dry hydrological rhythms is very important to maintain the dynamic balance of accumulated sediment and TP in the reservoir. The study does not only provide the effective calculation method forthe TP flux, accumulation and retention rate in the large reservoir, but also partly supply a new eyesight on the sediment nutrient control and related continuable management  for large reservoirs in north China.

How to cite: Huang, G., Li, X., Sun, M., and Lei, K.: Study on the concentration, flux, occurrence and retention processes of total phosphorus in Dahuofang reservoir, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6173, https://doi.org/10.5194/egusphere-egu21-6173, 2021.

11:19–11:21
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EGU21-5695
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ECS
Lin Liu and Qihua Ran

Non-sequential response, the phenomenon that the water storage change in the lower layer bigger than that of the adjacent upper layer within a set time interval, is often ignored because of lacking of distributed measured data at watershed scale, especially in mountainous area where extensive monitoring network is expensive and difficult to deploy. In this study, the subsurface non-sequential response in a mountainous watershed in Southwest China was investigated, combining field monitoring and numerical simulation. A physics-based numerical model (InHM) was employed to simulate the proportion and position of occurrence of the subsurface non-sequential response. The topographic wetness index (TWI = ln(a/tan b)) was adopted to distinguish the topographic zone corresponding to the non-sequential response occurrence at different depths. The results showed that the storage change in deep layer is not as fast as that in shallow and middle layers due to less disturbance, and the non-sequential response mainly came from the subsurface lateral flow which accumulated at the soil-bedrock interface. During a rainfall event, the shallow soil layer responded rapidly, the saturation increased, the non-sequential response moved from the hillslope zone in the middle layer to the channel zone in the shallow layer, and accumulated gradually at the soil-bedrock interface. In case of double-peak rainfall event, the occurrence proportion of non-sequential response increased, the depth expanded vertically, and the accumulated response shifted from the channel zone to the hillslope zone, which would affect the outlet runoff. Counter to the subconscious, non-sequential response could still happen even when precipitation stopped. The results improve our understanding of non-sequential response and provide a scientific basis for flash flood research in mountainous areas.

How to cite: Liu, L. and Ran, Q.: Non-sequential response in Mountainous Area of Southwest China, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5695, https://doi.org/10.5194/egusphere-egu21-5695, 2021.

11:21–11:23
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EGU21-15988
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ECS
Yiwen Zhou and Zhaoxia Li

Agricultural non-point sources (ANPS) pollution are considered to pose risks to water quality in Three Gorges Reservoir Areas (TGRA), especially when those pollution source comes from the hydrologically sensitive areas (HSAs) that generate surface runoff pathways. Therefore, it is necessary to identify the critical source areas (CSAs) or the sensitive regions of pollutants from agricultural lands in order to control and mitigate ANPS pollution effectively. In this study, an improved method integrating the Phosphorus Index (PI) and the Soil Topographic Index (STI) was applied to predict the risk of phosphorus loss and delineate the CSAs of phosphorus in a typical agricultural watershed in TGRA, China. The results showed that using a STI threshold value of 8.5, the HSA was identified 22.08% of watershed areas. The intersection of above two parts account 5.47% of the total watershed, compared with 24.41% of watershed areas based on an existing approach that uses just one criterion. As the results showed , the CSAs of phosphorus loss were mainly located near streams, with high or relatively high soil phosphorus contents or phosphorus fertilizer, or intense soil erosion are observed. The calculated results are in good agreement with the actual situation. Since the approach is based on GIS, and is a relatively simple application uses readily available geospatial data, therefore the technic could be used to improve cost-effectiveness and provide a useful screening tool for water resource managers responsible for identifying and remediating critical NPS source areas. 

How to cite: Zhou, Y. and Li, Z.: Phosphorus critical source areas identification in an agricultural watershed of Three Gorges Reservoir Area, China, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15988, https://doi.org/10.5194/egusphere-egu21-15988, 2021.

11:23–11:25
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EGU21-5439
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ECS
Tianliang Jiang and Xiaoling Su

Although the concept of ecological drought was first defined by the Science for Nature and People Partnership (SNAPP) in 2016, there remains no widely accepted drought index for monitoring ecological drought. Therefore, this study constructed a new ecological drought monitoring index, the standardized ecological water deficit index (SEWDI). The SEWDI is based on the difference between ecological water requirements and consumption, referred to as the standardized precipitation index (SPI) method, which was used to monitor ecological drought in Northwestern China (NWRC). The performances of the SEWDI and four widely-used drought indices [standardized root soil moisture index (SSI), self-calibrated Palmer drought index (scPDSI), standardized precipitation-evaporation drought index (SPEI), and SPI) in monitoring ecological drought were evaluated through comparing the Pearson correlations between these indices and the standardized normalized difference vegetation index (SNDVI) under different time scales, wetness, and water use efficiencies (WUEs) of vegetation. Finally, the rotational empirical orthogonal function (REOF) was used to decompose the SEWDI at a 12-month scale in the NWRC during 1982–2015 to obtain five ecological drought regions. The characteristics of ecological drought in the NWRC, including intensity, duration, and frequency, were extracted using run theory. The results showed that the performance of the SEWDI in monitoring ecological drought was highest among the commonly-used drought indices evaluated under different time scales [average correlation coefficient values (r) between SNDVI and drought indices: SEWDI= 0.34, SSI= 0.24, scPDSI= 0.23, SPI= 0.20, SPEI= 0.18), and the 12-month-scale SEWDI was largely unaffected by wetness and WUE. In addition, the results of the monitoring indicated that serious ecological droughts in the NWRC mainly occurred in 1982–1986, 1990–1996, and 2005–2010, primarily in regions I, II, and V, regions II, and IV, and in region III, IV, and V, respectively. This study provides a robust approach for quantifying ecological drought severity across natural vegetation areas and scientific evidence for governmental decision makers.

How to cite: Jiang, T. and Su, X.: A novel index for ecological drought monitoring based on ecological water deficit: a case study of Northwestern China, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5439, https://doi.org/10.5194/egusphere-egu21-5439, 2021.

11:25–11:27
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EGU21-10712
Hongyan Wang, Xin Chen, and Guangyu Chi

The leaching pattern of phosphorus (P) from continuous fertilization is generally neglected in heavy-textured soils. Generally speaking, P is hard to migrate vertically compared with nitrogen (N) and potassium (K) especially in clay loam soils. However, our study has proved that P could be leached to the depth of 1 m below the groundwater under circumstances of heavy rainfalls and large temperature differences. Our research is based on in-situ soil column experiments to estimate the effects of soil P leaching in typical fertilization regimes of Northeastern China. Fertilization treatments include CK (No fertilizer), NPK (900 kg ha-1 of compound fertilizer), NPKS (NPK + straw return), NPKSM (NPK + straw return + 7.5 ton ha-1 of dried cattle manure compost), 80% NPKS (720 kg ha-1 of compound fertilizer + straw return), 80%NPKSM2 (720 kg ha-1 of compound fertilizer + straw return + 15 ton ha-1 of dried cattle manure compost). In 2019 and 2020, we collected 10 leachates of each treatment and determined the concentrations of TP (Total P), TDP (Total dissolved P), PP (Particle P), SRP (soluble reactive P), and DOP (dissolved organic P). The results showed that P leaching has obviously occurred after 5-year continuous fertilization, with the leaching ratio accounted for 0.61%-2.2% of total P input, and the ratio of PP to TDP was about 1:1. Furthermore, the leaching loss caused by chemical fertilizer was equivalent to that of straw application and low-dose manure fertilizer, while high-dose manure application significantly caused more P leaching losses than the other treatments. What’s more, manure addition mainly promoted the vertical movement of PP, while straw application chiefly increased the leaching ratio of TDP. 20% reduction of chemical fertilizer significantly reduced the leaching loss of TDP, with a ratio of 16%-17% compared to full-scale chemical fertilizer. Overall, in terms of slightest environment risks from P loss via leaching in this study, the excessive manure application appears to pose a long-term risk of vertical P migration than the inorganic fertilizer and straw amendment.

How to cite: Wang, H., Chen, X., and Chi, G.: Phosphorus Leaching effects of organic and mineral fertilizers on a clay loam soil through in-situ soil columns, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10712, https://doi.org/10.5194/egusphere-egu21-10712, 2021.

11:27–11:29
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EGU21-16225
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ECS
Jun Deng and Zhaoxia Li

Determining the impacts of environmental and socioeconomic factors on nitrogen (N) and phosphorus (P) loss in the watershed is critical to reducing non-point source (NPS) pollution. This paper, we set 13 sampling points in the main stream and tributaries of watershed and sampled every two weeks from 2018 to 2020 to monitor the total nitrogen (TN) and total phosphorus (TP) concentration in the waterbodies. Twenty-six potential influencing factors affecting the nitrogen and phosphorus loss in the watershed were selected. The partial least squares regression (PLSR) was used to determine the relationship between TN and TP concentrations in the watershed and the 26 selected potential influencing factors. The results showed that the mean TN concentrations and mean TP concentrations in the dry season (11.42 mg·L−1 and 0.09 mg·L−1, respectively) were both less than those in the wet season (13.20 mg·L−1 and 0.11mg·L−1, respectively). The optimal PLSR model explained 69.6%, 73.1% and 66.1% of the TN concentration variability, and 65.7%, 79.5% and 67.4% of the TP concentration variability during annual, dry season and wet season, respectively. According to the importance of the variables in the predicted value (VIP), topographic wetness index (TWI), planting structure (PS), interspersion and juxtaposition index (IJI), Orchard land use (OP), nitrogen fertilizer application (NF), per capita income (INCOME) and catchment area (AREA) were the key factors affecting TN concentration, whereas topographic wetness index (TWI), interspersion and juxtaposition index (IJI), population density (POP), slope gradient (SLOPE) and hypsometric integral (HI) were the key controlling factors of TP concentration. In addition, TN concentration was affected by cropland land use (CP) during the dry season and proportion of labor (LABOR) and per capita agricultural land area (ALA) during the wet season. TP concentration was affected by mean patch size (AREA_MN), phosphate fertilizer application (PF) and patch density (PD) during the dry season and residential area (RP) and values during the wet season. This study illustrates the impact of environmental and socioeconomic factors on NPS pollution, and can be used as a guide for effective NPS pollution control and water quality management.

How to cite: Deng, J. and Li, Z.: The impacts of environmental and socioeconomic factors on the non-point source pollution in a small watershed in the Three Gorges Reservoir Area, China, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16225, https://doi.org/10.5194/egusphere-egu21-16225, 2021.

11:29–11:31
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EGU21-3828
Yuanyuan Zhang, Jianen Gao, Zhe Gao, Youcai Kang, Zhaorun Wang, Lu Wang, Fanfan Zhou, Sixuan Liu, Xingyao Li, and Mingjuan Ji

Abstract: In view of the weak research on the rheological characteristics involved in the variation of the fluid movement caused by the storm runoff carrying a large amount of pollutants and sediments, this study uses the NDJ-5S rotary viscometer and the self-made slim tube viscometer of Northwest Agriculture and Forestry University. On the basis of the research, the influence of pollutants on the rheological characteristics of high-concentration sandy water flow is studied. The results show that the NDJ-5S rotary viscometer can be used well under the sand content of less than 300kg/m3. The double vertical tube slim tube viscometer made by Northwest A&F University can better simulate the sand content of 0~800kg/m3; The structure of flocculation between particles in sandy water flow will affect the viscosity of muddy water, and the concentration of sediment and other pollutants will have a certain impact on flocculation. Under the same conditions, the concentration of pollutants increases (0~440kg/m3), the viscosity coefficient of fluid increases (90%~114%), and the variation of sand content from Newtonian body to Bingham body is about 300~400kg/m3, The influence of pollutants on the variation points of rheological properties is not significant.

Keywords: pollutants; sediment; variation; viscometer; Newtonian fluid; Bingham fluid

Funding: This study was funded by the National Natural Science Foundation of China (No. 41877078, 41371276), Key research and development project of Shaanxi Province (2020ZDLSF06-03-01), National Key Research and Development Program of China (No. 2017YFC0504703) and Knowledge Innovation Program of the Chinese Academy of Sciences (No. A315021615). 

How to cite: Zhang, Y., Gao, J., Gao, Z., Kang, Y., Wang, Z., Wang, L., Zhou, F., Liu, S., Li, X., and Ji, M.: Influence of pollutants on rheological characteristics of sediment flow, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3828, https://doi.org/10.5194/egusphere-egu21-3828, 2021.

11:31–11:33
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EGU21-13866
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ECS
Cheng Zeng, RongChang Zeng, and BingHui He

Abstract: Outcrops of rock strata in the Karst Trough Valley Area often form angles with slopes, thus making micro landforms complicated and altering significantly paths of concentrated flows, and consequently bringing about great changes in characteristics of the flows. So, it’s important to study hydraulic characteristics of the concentrated flows relative to angle between rock strata and slope. To that end, a flume experiment, designed to have combinations of three slope gradients (10°,15° and 20°), three flow rates (5, 7.5 and 10 L·min-1) and six angles between the rock strata and slope (30°, 60°, 90°, 120°, 150° and 180° (0°)), was carried out. Results show that hydraulic characteristics of a concentrated flow varied significantly with the angle between the rock stratum and slope. Reynolds number (Re) of the concentrated flow changed with duration of the scouring in a complicated trend, but exhibited a significant trend of increasing with rising flow rate, and an insignificant one of changing with slope gradient. And it varied in the range of 517~3343 in the experiment. Darcy-Weisbach friction coefficient (f) of the concentrated flow increased with rising slope gradient and with scouring going on, but decreased with rising flow rate. And it varied in the range of 0.62~5.70 in the experiment. The relationship of Re with angles between rock strata and the slope was not significant, but that of f varied with combinations of slope gradient and flow rate. The coupling relationship between f and Re was influenced significantly by the angle between the rock stratum and the slope. It could be better described with a logarithmic equation when the angle between the rock stratum and the slope was narrower than 90°, and with a power function equation when the angle between the rock stratum and the slope was wider than or equal to 90°. In the experiment, when Re<1791, the relationship between f and Re was not apparent, but when Re>1791, it was significantly positive. To sum up, f and Re and their relationship vary with the angle between the rock stratum and the slope. The findings in this experiment may provide strong data support for establishing soil erosion prediction models in the Karst Trough Valley Area.

How to cite: Zeng, C., Zeng, R., and He, B.: Hydraulic Characteristics of Concentrated Flow Relative to Angle between Rock Strata and Slope in the Karst Trough Valley Area, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13866, https://doi.org/10.5194/egusphere-egu21-13866, 2021.

11:33–11:35
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EGU21-1466
Naseer Ahmed Abbasi and Xiangzhou Xu

Abstracts: Influenced by global climate change, water shortages and other extreme weather, water scarcity in the world is an alarming sign. This article provides evidences regarding the Tunnel and Tianhe project’s feasibility and their technical, financial, political, socioeconomic and environmental aspects. Such as how to utilize the water vapour in the air and to build a 1000 km long tunnel project to fulfill the goal of solving water shortage in China. The projects are promising to solve the problem of water, food and drought in the country. In addition, the telecoupling framework helps to effectively understand and manage ecosystem services, as well as the different challenges associated with them. Such efforts can help find the ways for proper utilization of water resources and means of regulation.

Key words: Sustainability; water shortage; transfer project

How to cite: Abbasi, N. A. and Xu, X.: Envisaged transfer projects: New technologies in the water sustainability, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1466, https://doi.org/10.5194/egusphere-egu21-1466, 2021.

11:35–12:30